The present invention relates to a data providing technique for providing useful information for users in real time, achieved by combining a personal communication mode which utilizes a network such as the Internet and a global data distribution mode such as a digital broadcast.
Digital broadcasts using cables, artificial satellites and ground waves are now very popular. The digital broadcasts include not only a mode for distributing program data to an indefinite number of persons in the general public as its objects (to be referred to as “normal distribution” hereinafter), but also a mode for delivering contents of movies, games and the like for particular persons at cost (to be referred to as “contents delivery”).
In the case of the normal distribution, a distributor prepares a broadcast station (to be called “host station” hereinafter) for distributing program data. A user side is equipped with an antenna, a digital receiving unit, a display unit and an audio unit, and program data transmitted from the host station is received through the antenna, and the received data is reproduced by the digital receiving unit in the form of a corresponding image and sound. More, specifically, the image is displayed on the display unit and the sound is outputted from the audio unit.
In the case of the contents delivery, a distributor prepares a server station for managing users of subjects to whom data should be delivered, in addition to the host station. A user side prepares an STB (set top box) which can be connected to a network such as the Internet, in addition to an antenna, a digital receiving unit, a display unit and an audio unit. In this specification, these units equipped on the user side are called “terminal device”. The server station and a terminal device are set up to receive or transmit data through the network.
When a user makes a request for contents to the server station via the terminal device and the network, the server station carries out identification of the user who made the request, and then transmits key data to be used for the restoration of the contents, which are encoded or scrambled, to the terminal device of the user. At the same time, the server station instructs the host station which performs the digital distribution, to transmit the ordered contents (encoded or scrambled) to the user.
The host station transmits the ordered contents upon the instruction of the server station.
The terminal device receives the distributed contents and restores the contents using the key data transmitted from the sever station. Of the restored contents, the image is displayed on the display unit and the sound is outputted from the audio unit.
In the above-described procedure, the user can enjoy the contents at cost.